Over a year’s experimentation with high-speed photographic techniques has paid dividends for Dunedin natural history photographer Nic Bishop. Enlisting the help of two electronics experts, and with financial backing from Shell New Zealand, he has succeeded in developing equipment to photograph insects in flight and freeze other action too fast to be seen by the human eye.
Photographing flying insects is one of the most demanding challenges of nature photography. Simply getting the insect to fly into the field of view of the camera is one hurdle, but even more problematic is getting the shutter to fire at the precise moment the insect is in focus. The speed at which many insects fly means that they remain in focus for a mere 1/500 of a second, necessitating virtually instantaneous detection and shutter opening. Then there is the need to freeze the insect’s wings on film—in some species the wings beat at 1000 cycles per second.
To tackle these problems Bishop built a flight tunnel and wired it with light beams and detectors able to respond even to the wing tip of a flying insect, and to operate the camera at the precise instant the insect zooms into focus. The conventional camera shutter was discarded, being about 25 times too slow at opening, and has been replaced by a modified shutter system.
Freezing the insect’s motion is done by exposing the subject with a very brief flash pulse. Once again, conventional flash equipment had to be dispensed with because it simply did not have the power and speed requirements. Instead, a new flash circuit was developed, one which delivers a light output equivalent to conventional units, but compressed within a pulse lasting only 1/40 as long. This pulse, a mere 1/40,000 of a second duration, is brief enough to stop even the most active animal in mid-motion.
The project has not been without teething problems. For example, the voltages unleashed by the flash circuits are so high (lethally so) that they have blown up flash tubes with explosive finality. At the other end of the scale, the detection circuitry is so sensitive that it can respond to outside interferences such as temperature fluctuation, vibrations, and electrical perturbations in nearby equipment.
With the system now working, Bishop has been exploring the high speed action of some of New Zealand’s smallest inhabitants, and some of his initial results can be seen in his latest book Natural History of New Zealand, published by Hodder and Stoughton.